Mandrel



ically locked to clamp a tool in Patented Jan. 15,

UNITED STATES PATENT" OFFICE.v

f 1,987,839 f` f s MANDREL William A. Kelsey, Minneapolis, Minn. v Application June 24,1932, serial No. 619,129 11 claims. (c1. 32k-'59) The object of myV inventionis to provide an limited rotation toits clamping position with means whereby the jaw will becomefautomatthe mandrel at the end of a predetermined rotary movement' in either direction, theeffect being that a smoothing or polishing disk or other -tool supported by the mandrel will become firmly held therein whether the disk or tool is rotated forward or backward.

A further object is to provide a mandrel with relatively fixed and movable jaws and a compensating lock device which will automatically lock the jaws' against separation while adapting them for use with rotating disks, saws or other tools of varying thickness.

A further object is to for the tool supporting the locking pressure on to the resistance of th or grinding' faceof the provide a locking means jaw which will increase the tool proportionately e work onthe polishing tool, whereby as the tendency of the tool and its supporting jaw to turn increases, the greater will be the pressure to prevent such turning.

A further object isV to provide means within control of the user of the mandrel to normally preventseparation of `the rotating jaw from the xed jaw and the release of the tool held between them until the operator moves such means to its release position. 4

Other objects of the invention will appear from the following detailed description. The invention consists generally in various constructions and claims.

In the accompanying of this specification,

combinations, all as hereinafter described' and particularly pointed .out in the drawing' forming part Figure 1 is a view of a mandrel embodying my invention Figure 2 isa longitudinal sectional view through the mandrel in its clamping position;

Figure 3 is a similar -view showing'fthe. jaws of the mandrel separatedto 'release a polishing disk orI other tool;

Figure 4 is a detail vieW of the upper portion of the member'of the mandrel formingfthe' movable jaw; Figure' 5 is a sectional view looking at the underside of the movable jaw;

` Figure 6 is a top View of the:` cup-shaped member, the flange of which formsthe4` fixed jaw 'of the mandrel;

l vFigure '7 is avvertical sectionalview through thisvcup-shaped member showing the preferred manner of mounting iton the shank of' the mandrel, and also showing the cam surfaces-for interlocking engagementv with the lugs of the movable jaw; i y f f Figure 8 is a sectional view on the line'88 of Figure 2;. i i Figure 9 is a .sectional view on the line 9-9 of Figure 3; f

yFigure 10 is a sectional viewon thefline 10-10 of Figure 3; .i 1 Figure 11 is a detail view of one ofthe locking, keys for holding the movable jaw in its clamping position.

In the drawing 2 `represents the shank of the mandrel havinga longitudinal bore 3 therein. A stem 4 is adapted to slide in said bore and has a disk 5 `at one end provided on the underside with a depending flange 6 between which andthe fixed jaw of the mandrel the'diskor other vtool may be clamped. The outerend of the shank vhas a hub "I` thereon to receive a cupshaped member 8 provided with an annular wall `9 which terminates in an inwardly projecting ange 10'at thel upper vedge of the wall, this flange forming'the xed portion of the jaw upon which the tool' is seated. The flange 10 has op- `positely arranged notches 11 and between" these notches uporvopposite 'sides thereof I prefer to provide depending liange members 12 having i camsurfaces 13. Depending studs 14 are provided on the disk 5 terminatingin outwardly projecting lugs 15 having beveled faces .16 which engage the cam surfaces 13- and limit the rotary lmovement ofthe movable jaw and the stem thereof. These studs have lower edges y17 which pierce the paper orother fibrous material when a, disk of this material is used in the mandrel. When the parts of themandrel are assembled the studs` and lugs havingvpassed through the tool will'pass throughthe'notches 11 and enter the Ycup-shaped "member 8 a sufficient distance toallow the vtool to .be clamped between the fixed and movable member; The movable jaw 5 may then'be rotated in either direction until the faces 16 .of .the studs 15 engage the cam Vsurface'sali and thereupon the .jaw will be locked lin its clamped position and the fpolishing or smoothing diskorotlier tool'will 'be firmly held." Usual; ly in applying a tool ofv this kind tothe `work there will lbea tendency to `rotate it..andthe clamping jaw and Ywhen this takes placethe: lugs 15 will slide onthe cam surfaces y13 andgradlually tighten the'grip ofthe jaws andthe double arrangement ofcthese cam surfacesandthe cor-` responding faces of the lugs will produce this clamping effect regardless of which direction the polishing disk, saw, or other tool is rotated.

During the rotation of the movable jaw it would be possible for an accidental separation to be effected of one jaw from the other at the point where the lugs 15 are in register with the notches 11 in changing the direction of the rotation of the tool, and for the purpose of preventing tbis possible wseparation `and positively controlling fitherelease of the tool and adapting the mandrel for tools of different thicknesses, I have provided an automatic locking means for the stem 4 which I will now describe in detail.

The shank 2 has an enlarged portion 18 provided with a series of longitudinal slots 19 arranged at intervals and extending lengthwise of the shank and communicating with the central bore 3. The vstem 4 is provided with an inclined surface 20 which when the parts of the mandrel are assembled will :be opposite the slots 19. A collar 21 is provided on the shank encircling thelower portion :of the slots 19 and is provided with an inner downwardly (daring annular surface 22 that is opposite the surface 20 andparallel substantially therewith. A yseries of keys 23 fit within the slots 19 and have wedge-shaped heads 24 4at their Alower 'ends for contact with the surfaces 20 and 22. 'Ihe upper en'ds of these keyshave outwardly yproje'ctingllugs 25 and ears 25 which slide on the walls of the slots :and prevent inward movement `of the keys and their `displacement inthe slots. A coil spring 26 is seated on the collar 21 and a :dat ring27 vrests on thisspring 4and forms a supportfor .the lugs 25 and the keys. A sleeve 28 encircles the spring 26 and the locking lkeysand is .slidable on the collar `21 and has an inwardly `projecting flange 29 which 'bears on the lugs '25 of the locking keys. This Isleeve is free to `slide lengthwise upon the mandrel under 'pressure of the fingers Yo1' the operator, and vwhen -it is pushed downwardly and the `spring 26 '.compressed, the wedge-shaped heads 24 of the keys will slide fdown between the surfaces 20 'and 22 and release the stem 4, allowing it to Abe pulled out of the shank of the mandrel, at'which time a disk `or yother tool may .fbe placed on the fixed jaw, thestem inserted throughthe central opening in the disk'and the lugs on fthe movable jaw pressed through the disk to their locking position, and when this has been done the operator will re- `lease Vtl'iesleeve 28 vand allow it 'to return to the vposition shown in Figure `2, where the locking keys will lie in the path of 'the inclined surface 20 of the stem 'and positively prevent the stem from beingpulled out of the shank.

The disk `or vother tool will be held between the :jaws 'of 'the mandrel and forward or backwardrotation 4of the tool will be permitted, the movable fjaw rotating vfrom one locking position 'to the `other and during this change in the direction of rotation of the tool it'will be impossible for the movable jaw to become released fand separated from the fixed 'jaw when the studs .14 are in register with the notches 11 as fthe stem 4 will at that time be securely held vby thelzocking keys, and while rotation `of the stem is ipermittedit will 'be securely held against outward longitudinal 'movement Whenever desired, the operator grasping lthe s1eeve'28may push downwardly thereon, as 'illus- -trated in Figure 43, andmove the locking keys to `their release position, as indicated in this wregftherebypennitting the stem 4 to be pulled outwardly and the movable jaw separated a sufficient distance from the fixed jaw to release the disk or other tool that has been clamped between them.

The tapered surface on the stem and the corresponding surface of the encircling collar allows the locking device to automatically compensate for varying thicknesses of the tools that may be inserted between the jaws. The operator Aof the lmandrel may at one time -desire to clamp a comparatively l"thin disk :and then immediately thereafter have use for a thicker disk, saw or other tool and regardless of the variation in the thickness of the tools the locking device will automatically adapt itself to positively hold the jaws against premature separation, while at the same time freedom of rotation of one jaw with respect to the other is permitted, and during this rotation and when the jaws are at the point where separation is permitted in passing from one Acam .surface to another, 'the lock will positively hold the jaws together until such time Vas it is moved to the release position by theoperator.

With this mandrel, the operator may easily and'quickly clamp a Vpaper disk, saw lor Iother toolvarying in thickness in place and rotate -it forward or backward as maybe desired in the operation of the mandrel, `and this forward or backward movement may be accomplished without danger of releasing the tool or disengaging -themovable jaw from the fixed jaw.

This invention, while adapted particularly for use as a dentalmandrel, may be incorporated in mandrels adapted for other purposes where it is desirable to adapt the device for gripping disks or tools of different thicknesses and where a forwarder backward movement of the tool is desirable without affecting the gripping or clamping elements.

I claim as my invention:

'1. A dental mandrel having ya Afixed jaw provided :with a, cavity anda flangeencircling said cavity provided with oppositely arranged notches, a movable jaw having Vstuds provided vwith heads to entersaid notches and rotate forward or backward in said cavity, the inner walls of said fixedjaw having surfaces cooperating with the surfaces of .said heads whereby said movable jaw will `'become locked when rotated a predetermined distance in either direction, 4and said `heads and studs being adapted yto puncture a disk preparatory to clamping it between said Jaws.

2. A dental mandrel comprising a shank having a bore therein, a xed jaw on said shank, a movable jaw having a stem slidable in -said bore, said movable jaw having studs thereon and said fixed jaw having notches to receive said studs, and said studs and the inner walls of said fixed jaw having cooperating surfaces for limiting the rotary movement ofsaid movable jaw in either direction, and simultaneously drawing the jaws together to clamp a tool between them, and

`said shank having means whereby the premature separation of said movable and fixed jaws is prevented when 'its studs are in register with said notches during the forward or backward rotation of said movable jaw.

3. A mandrel comprising a shank having a xed jaw thereon 'and provided with a longie tudinal bore, Ya movable jaw having astem to "slide -in said bore and provided with an inclined surface, a collar encircling said stem and having an inner 'corresponding surface, :a series of spring-pressed locking keys slidable in slots provided in the Walls of said shank between said collar and stem and having surfaces for normally contacting with the opposing surfaces of said stem and collar to lock said stem against premature outward movement, and a sleeve encircling said keys and shank whereby the operator may move said keys to their release position against the tension of said spring.

4. A mandrel comprising a shank having a longitudinal bore therein and provided with a i'lxed jaw, a movable jaw having a stem to enter said bore and rotate and slide therein, a collar encircling said shank and stem, a series of locking keys interposed between said stem and collar and having surfaces coo-perating with surfaces on said stem and collar for normally locking said stem against outward movementl while permitting rotating movement thereof, said jaws having cooperating means whereby their clamping surfaces will be drawn together as said stem and movable jaw are rotated, said keys during such movement locking said stem against outward movement, and means whereby the operator may move said keys to their release position and allow the separation of said jaws.

5. A mandrel comprising iixed and movable jaws having a relative rotary movement, means whereby such rotary movement in either direction will draw said jaws together to clamp a tool between them, the degree of pressure on the tool increasing proportionately with the relative rotation of the jaws, said means allowing separation of said jaws at a predetermined point in their rotation and means whereby premature separation of said jaws is prevented.

6. A mandrel comprising a shank provided with a longitudinal bore and having a fixed jaw thereon, a movable jaw having a stem to enter said bore and slidable therein to allow said movable jaw to be adjusted in its locking or releasing position, the stem of said movable jaw having an inclined surface thereon, a collar on said shank encircling said stem and having an inner inclined surface opposite and spaced from the corresponding surface of said stern, locking keys interposed between said stem and collar and having surfaces cooperating with the inclined surfaces of said stem and collar to normally lock said stem and movable jaw in any of their adjusted clamping positions, and means for moving said keys to a release position and allow adjustment of said stem to compensate for varying thicknesses of the tools between said `jaws.

7. A device of the class described comprising clamping members driving and driven, means by which one member is rotatably and translatably journaled in the other, means by which the members are coupled as a result of axial translation and only when the members have a predetermined rotative angular relation to one another, means by which after coupling, said members are moved to clamping relation as a result of rotative motions in either direction from the coupling position, and means for preventing translative uncoupling of the members but permitting rotation therebetween as a result of reversing rotations of the driving member.

8. A device of the class described comprising clamping members driving and driven, means by which one member is rotatably and translat- 'ably journaled in the other, means by which the members are coupled as a result of axial translation and only when the members have a predetermined angular relation to one another, means by which after coupling said members are moved to clamping relation as a result of a predetermined degree of rotative motion in either direction from the coupling position, and means for preventing translative uncoupling of the members.

9. A device of the class described comprising clamping members driving and driven, means by which one member is rotatably and translatably jounaled in the other, means by which the members are coupled as a result of axial translation and only when the members have a predetermined angular relation to one another, means by which after coupling said members are moved to clamping relation as a result of rotative motion from the coupling position, and means for preventing translative uncoupling of the members, said coupling means being adapted to traverse openings in a tool which is to be clamped between said members.

l0, A mandrel comprising a xed jaw and a movable jaw, the movable jaw having a pin which is rotatable and translatable in the xed jaw, means by which rotary movement of the movable jaw, 1n either direction will draw the same toward the xed jaw proportionately to a degree of rotation to clamp a tool between the jaws, means on the fixed jaw automatically locking the pin of the movable jaw to prevent separation of the jaws, and means manually movable to move said automatic locking means to unlocking position.

l1. A mandrel comprising iiXed and movable jaws, the movable jaw having a pin rotatable and translatable in the xed jaw, said pin having a portion oonvergently tapering in a direction toward the cooperating point of the jaws, means by which rotative movement of either jaw will draw the jaws together to clamp a tool between them, means operating automatically on the tapering portion of the pin for automatically preventing unlocking withdrawal of said pin, and means manually operable for moving said last mentioned means to permit withdrawal of the pin.

, WILLIAM A. KELSEY. 

